1. Field of the Invention
The present invention relates to the field of handguns, and more particularly semiautomatic handguns.
2. Prior Art
An automatic pistol carries a slide/barrel assembly that slides longitudinally along a frame. A spring braced between the slide and frame holds the slide/barrel assembly in a forward and closed position. A cartridge chamber exists within this slide/barrel assembly. In the forward position, the rear end of the barrel is covered by the breech face upon the slide. A hole in the breech face provides access to the cartridge chamber for a firing element to pierce the primer of the pistol cartridge, thereby discharging the cartridge and expelling the bullet.
The firing element can be driven forward by a hammer striking it, or it can be moved backward under spring pressure and released to drive the firing element forward through the breech face to the primer. In either instance the hammer or the firing element itself is connected through mechanical means to a trigger operated by the user.
Upon discharge of a pistol cartridge, a bullet travels forward out through the barrel, the slide/barrel assembly moves rearward for a specific distance where the barrel moves slightly downward and stops, the slide continues to move rearward opening the cartridge chamber. The extractor (through spring pressure) holds the spent cartridge casing to the breech face, removing it from the barrel. As the slide continues rearward, the ejector (mounted in the frame) contacts the spent cartridge casing, pushing it away from the breech face, causing the extractor spring pressure to be overcome to expel the empty cartridge from the pistol.
Now at maximum rearward travel, the slide has cleared the magazine assembly, allowing the next cartridge in the magazine to move up (magazine cartridges are loaded under spring pressure). Spring pressure pushes the slide forward contacting the next cartridge from the magazine and delivering it to the cartridge chamber which closes as the slide moves forward. Slide fully forward, the pistol is loaded ready to fire again.
This generally describes the operation of an automatic pistol with a locked breech mechanism, fired either by striker or hammer operation. A straight blowback mechanism operates similarly. However, the barrel is not part of a slide/barrel assembly; it is integrally and rigidly mounted to the frame. The slide, containing the breech face, is held forward closing the cartridge chamber only by spring force and with no particular mechanical interlock.
Whether hammer or striker fired, various pistol mechanisms are employed to facilitate the forward movement of the firing element:
In a DAO (Double Action Only) mechanism, actuating the trigger pulls back the hammer (or striker) to a critical point and then releases it in one smooth motion.
In a single action mechanism, the pistol must be manually “cocked” by racking the slide rearward or by pulling the hammer back. Trigger actuation will then release the “cocked” element driving the firing element forward through the breech face. Following the initial discharge of the pistol, sequential shots may not require manually “cocking” of the firing element, as the pistols operation will leave the device in a “cocked” condition following each firing.
Specific to the Glock firearm (U.S. Pat. Nos. 4,539,889, 4,825,744 and 4,893,546) is an intermediate action mechanism. This device works like a single action mechanism, however, it has characteristics of the DAC as well. It must be manually “cocked” before the first discharge, and sequential firings require only trigger actuation. The sequential trigger operations do not solely release a firing element, however (as in the single action design), they serve to actuate the firing element from an intermediate position to the critical point where release takes place, actuating the firing element. This design allows a trigger pull distance that is less than in the DAC and greater than in the single-action. Most importantly, it maintains the firearm in a partially “cocked” position where accidental discharge by dropping the weapon is impossible (a single action design makes inadvertent discharge through dropping prevalent), since the intermediate position of the firing element does not have enough spring tension to drive the firing element through the breech face if released.
Classically, semiautomatic handguns have been substantially all metal, except for the handgrip, which often included plastic, wood or other material for comfort and esthetic purposes. More recently, plastic has been sometimes used in other parts of semiautomatic handguns as a means of cost reduction, though typically in conjunction with metal parts that define the critical operating parts and surfaces. As such, the metal parts are still relatively expensive because of their complexity and machining requirements, thereby limiting the cost reduction that can be achieved.